The cognitive load of a teacher is extremely high:
I love it when folks bring together disparate points from seemingly unconnected sources, as you have here. I think your comments about cognitive load are apt, as some research says that teachers are making up to 1500 decisions in a single day (http://www.teachthought.com/teaching/teacher-makes-1500-decisions-a-day/). This is a HUGE cognitive load, and one that definitely does require breaks.
However, I wonder if a lot of the cognitive load issues that we see in many classrooms is in the very role of what we think an “ideal teacher” should be. Many teachers feel as though they have to be the one expert in the room, and yet there are so many other sources of expertise and “teaching” that they can rely upon. Whether it is in creating a community of learners to help support one another or in relying upon digital resources and tools, the cognitive load is lessened each and every time the teacher does not have to be the sole source of information and knowledge in the classroom. It doesn’t necessarily make the teacher’s job any easier, but it can make it so that at least some of those 1500 decisions are made by the students or the adaptive tools that the teacher uses.